Burden of Disease from Contaminated Drinking Water in Countries with High Access to Safely Managed Water: A Systematic Review

Abstract

BackgroundThe vast majority of residents of high-income countries (>90%) reportedly have high access to safely managed drinking water, the highest level of service under the Sustainable Development Goal (SDG) framework. Owing perhaps to the widely held perception of near universal access to high-quality water services in these countries, the burden of waterborne disease in these contexts is understudied.MethodsWe conducted a systematic review of estimates of the disease burden attributed to drinking water in countries where >90% of the population has access to safely managed drinking water per official SDG monitoring. We searched PubMed, Web of Science, and SCOPUS for articles published before September 10, 2021.FindingsWe identified 24 studies reporting estimates for the disease burden attributable to microbial contaminants. Across these studies, the population-weighted average burden of gastrointestinal illness risks attributed to drinking water was about 3,529 annual cases per 100,000 people. Beyond exposure to infectious agents, we also identified 10 studies reporting disease burden, predominantly, cancer risks, associated with chemical contaminants. Across these studies, the pooled population-weighted average of excess cancer cases attributable to drinking water was 1.8 annual cancer cases per 100,000 people.InterpretationThese estimates exceed WHO-recommended normative targets for disease burden attributable to drinking water and highlight that there remains important preventable disease burden in these contexts. However, the available literature was scant and limited in geographic scope, disease outcomes, range of microbial and chemical contaminants, and inclusion of subpopulations that could most benefit from water infrastructure investments. These subpopulations include rural, low-income communities; Indigenous or Aboriginal peoples; and populations marginalized due to discrimination by race, ethnicity, or socioeconomic status. Studies quantifying drinking water-associated disease burden in countries with reportedly high access to safe drinking water, with a focus on specific subpopulations and promoting environmental justice, are needed.Research in contextEvidence before this studyAlthough the burden of disease associated with unsafe drinking water in low- and middle-income countries has been subject of much research, there is uncertainty about the magnitude and nature of this disease burden in high-income countries and countries where access to safely managed drinking water is >90%. To assess the magnitude of this burden in countries with high levels of access to high quality water, we conducted a systematic review of estimates of the disease burden attributed to drinking water in countries where >90% of the population has access to safely managed drinking water as defined by the WHO/UNICEF Joint Monitoring Programme for Water Supply, Sanitation and Hygiene (JMP). We searched PubMed, Web of Science, and SCOPUS for relevant articles published before September 10, 2021. We searched for articles including “burden of disease” OR “disease burden” OR “gastrointestinal illness” anywhere in the text. From among these articles, we selected those with the terms “drinking water” OR “tap water.” From this reduced set, we selected articles reporting on countries with >90% safe water access and including estimates of cases, hospitalizations, or deaths related to drinking water contamination. Additional articles were identified from consultations with subject-matter experts. Only articles in English were recovered, which may have biased our results towards specific countries.Added value of this studyTo our knowledge, this is the first global review of its kind to identify burden of waterborne disease estimates associated with microbiological contaminants as well as chemical contaminants found in drinking water, specifically in countries with reportedly high access (>90%) to safely managed drinking water. Despite the perception that high quality water is ubiquitous in these countries, we found that burden estimates in these countries exceeded WHO-recommended targets for disease burden attributable to unsafe drinking water. This review also highlighted the gaps in our understanding of waterborne disease burden across and within countries where access to high quality drinking water is common.Implications of all the available evidenceEven though the levels of access to safely managed drinking water are high in many high-income and some middle-income countries, there remains a potentially important preventable disease burden in these high-income countries. Our review suggests that further burden research expanding the scope of contaminants, disease outcomes, geographic area, and vulnerable subpopulations within countries is necessary. Currently, available evidence is insufficient to support rational decision-making and to prioritize public investment to protect the health of marginalized communities. These groups include rural, low-income communities; Indigenous or Aboriginal peoples; and populations marginalized due to discrimination by race, ethnicity, or socioeconomic status.

Social Vulnerability and Exposure to Private Well Water

“…It has been noted in other studies that a lack of access to safe drinking water in the United States is associated with race/ethnicity, as well as poverty. 49,50 In a study of environmental injustice regarding a population's nearness to unconventional gas development in the state of Pennsylvania, Clough and Bell in 2016 found that race and ethnicity were not associated with proximity to unconventional gas development, but poverty was. 20 With regards to minority race and/or ethnicity, we found that the census tracts with the highest proportions of minority populations were more likely to have access to public water.…”

“…Approximately 90% of the US is considered to have access to safely managed drinking water 17,49 , which in the context of the US is deceiving, as this number includes those served by private, unregulated, untested and untreated domestic wells. If we were to say that only those served by public drinking water in US have access to safely managed drinking water, then this number would be drastically decreased.…”

Progress toward alleviating preventable waterborne diseases over the past 30 years

“…The obvious case in point is the extreme inequities faced in Flint, Michigan among lower-income neighborhoods due to lead exposure (e.g., Campbell et al, 2016). Unfortunately, other examples abound and are more often than not the result of systemic racism and a history of racist policies within societies (Brown et al, 2023;Lee et al, 2023).…”

Public Concern about Water Safety, Weather, and Climate: Insights from the World Risk Poll

“…Today, water safety is a particular concern in low-income countries in the Middle East, Northern Africa, Central Asia, and Southern Asia, due to rapidly expanding urban areas, hobbled water infrastructure and distribution systems, and limited resources to address water crises. , Indeed, low-income countries tend to have fewer safeguards against unsafe drinking water, as indicated by Yale’s Environmental Performance Index . However, a recent review highlights that threats to water safety also affect residents of high-income countries in the Global North, especially those who live in rural households that rely on private wells for drinking water. , The United States Environmental Protection Agency (EPA) estimates that 23 million American households rely on private wells, which are prone to contamination. , Even in countries in which at least 90% of the population had access to safely managed water sources, 3,529 per 100,000 people yearly are estimated to develop gastrointestinal illnesses attributable to drinking water …”

“…14,15 Even in countries in which at least 90% of the population had access to safely managed water sources, 3,529 per 100,000 people yearly are estimated to develop gastrointestinal illnesses attributable to drinking water. 16 To protect against unsafe drinking water, agencies such as the United States Centers for Disease Control and Prevention (CDC), 17 United Nations Children's Fund (UNICEF), 18 and the EPA 19 bottled water for emergencies and treating potentially contaminated water by boiling or with chemicals (e.g., chlorine, diluted bleach). For well owners, it is also important to regularly monitor and test water quality.…”